What the H am I doing wrong?? Maverick Slugs..

I also have the Maverick Compact. Started off with the 500mm .25 STX barrel and tried slugs but realized the Maverick didn't have the power for .25 slugs. I switched out the barrel to a 600mm .22 STX barrel and bought every light NSA slug (under 30 grains) had. I also tested FX Hybrids, Zans, Rat Snipers, and several H&N slugs. I bought Huma's slug kit and started testing. After weeks of testing, this is what I hope is the best combination for accuracy. I have the stock hammer, Huma probe, Regs at 170 and 150, KO 25.39 grains, Ave speed is 965, and I think my shot count is about 40. I don't remember what the length for the hammer is set at but if you look up 910 videos on tuning the Maverick, the information will be there. I just kept it at where it says in the video.
At this setting, I can easily shoot soda cans at 150 yards which is the furthest I tested. One thing I noticed testing slugs is they normally don't out shoot pellets inside 50 yards or if you have a calm day. In my observations, slugs out perform pellets in windy environments. The reason I stated this is if you see slugs not performing as good as pellets in calm or short ranges, this normally what I also saw and not to be discouraged. YouTuber celebs make it seem slugs are the pinnacle for accuracy but you have to realize they are paid to push a product.
 
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👆This is more good advice. I had to make sure I didn’t write it. What we want or expect with slugs can be completely different than what actually happens. I only believe about 25% of what I read or hear. One hint is you don’t ever see a slug edition with a 500mm barrel. Not that it can’t be done, but the longer the barrel the broader your tuning options.
 
Well, where I'm going to get ground squirrels is...mixed, calm some days and windy as hell on others. My usual range is from 50 to 75 yards, absolutely zero cover so the darn rodents spot you.
I also have the Maverick Compact. Started off with the 500mm .25 STX barrel and tried slugs but realized the Maverick didn't have the power for .25 slugs. I switched out the barrel to a 600mm .22 STX barrel and bought every light NSA slug (under 30 grains) had. I also tested FX Hybrids, Zans, Rat Snipers, and several H&N slugs. I bought Huma's slug kit and started testing. After weeks of testing, this is what I hope is the best combination for accuracy. I have the stock hammer, Huma probe, Regs at 170 and 150, KO 25.39 grains, Ave speed is 965, and I think my shot count is about 40. I don't remember what the length for the hammer is set at but if you look up 910 videos on tuning the Maverick, the information will be there. I just kept it at where it says in the video.
At this setting, I can easily shoot soda cans at 150 yards which is the furthest I tested. One thing I noticed testing slugs is they normally don't out shoot pellets inside 50 yards or if you have a calm day. In my observations, slugs out perform pellets in windy environments. The reason I stated this is if you see slugs not performing as good as pellets in calm or short ranges, this normally what I also saw and not to be discouraged. YouTuber celebs make it seem slugs are the pinnacle for accuracy but you have to realize they are paid to push a product.
Thanks for the reply. You didn't say if you used the slug side or the pellet side. I would assume the slug side. But I dislike assuming.
 
Well, where I'm going to get ground squirrels is...mixed, calm some days and windy as hell on others. My usual range is from 50 to 75 yards, absolutely zero cover so the darn rodents spot you.

Thanks for the reply. You didn't say if you used the slug side or the pellet side. I would assume the slug side. But I dislike assuming.
Slug side
 
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I’ve got a 25 Maverick compact with standard (I believe ) liner and it does quite well will 26 grain NSA slugs at around 915 fps. I wouldn’t say they stack in one ragged hole like pellets can at 50 but it’s pretty darn good. I’ve got like 1300 of them so going to use them up. It does this speed very consistently with 120 bar second reg. Not sure exactly where the internal HS is but power wheel is 7.
 
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Ok, I give up, I've got a Maverick .22 Compact, I've got both FX Hybrid's 22gr and RMR 22gr slugs and I can't get them to work for beans, bumped up the reg pressure, standard liner running the slug side of the transfer port, heavier spring and weight, Huma and yet, I can't get the darn things to go fast enough.
What is your speed with these slugs?
 
that's the point I can't get then over 900. I've literally tried everything. I can shoot them out of my Sapsan but I'm beating the poor thing to death doing it, so, I've given up that gun.
Yeah, definitely doing something wrong. The maverick is absolutely capable of getting above 900 with slugs in compact form. What’s your reg pressure at? Are you overpowering the reg with you aftermarket heavy hammer? This won’t give you more power, just wasted air.
 
Yeah, definitely doing something wrong. The maverick is absolutely capable of getting above 900 with slugs in compact form. What’s your reg pressure at? Are you overpowering the reg with you aftermarket heavy hammer? This won’t give you more power, just wasted air.
Stock hammer, stock spring currently at 103, pellet port. Even on the slug port I couldn't get it up there. I'm going to mess with it the end of the week, I just set it up for ground squirrels on Wed, not playing with it any more. BUT as an aside, I've now developed a SLOW leak, as in 10 bar/hr. My gut feeling is a regulator has decided to go south. Time for some soapy water.
 
I swear I remember someone else talking about this recently and they had an issue with a part on the gun. Will continue searching for that post in a bit....

Just trying to establish as many facts as possible here so wondering a couple things.
First, have you shot pellets with a chrono to see a baseline before slugs? Does the power wheel work as intended with increasing velocity with the lowest at 1 (or the adjust hole if we are being particular) and highest reading at 7?

Second, can you verify WHICH stock hammer is in it. That one should have come with the 7 gram hammer, but an 11 gram in it could cause issues at the pressure you are stating on 2nd reg.

Third, for shooting slugs you really may want to contact FXUSA and order yourself an 11 gram hammer. The Compact in particular does want higher pressures than the Sniper and you need that 11 gram hammer to shoot in the upper 900s with some middle weight slugs.

Fourth, once you get it ironed out I would really recommend checking out Knockouts. For me in .22 those actually shot very well at 1000fps AND at 900fps. Ground squirrels at 75 yards would be no problems with a Knockout at 900.
 
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I have a Wildcat Mk3 BT 500mm shooting the 23 grain Javelin 218s at 950fps and it’s very accurate and consistent. I understand that it has the same guts as the Maverick so you should be able to copy what I did:

To get adequate hammer, I used the stock spring with a Huma 14.5g hammer from their maverick/wildcat/dreamline/etc hammer weight tuning kit. Also used slug probe and pin. No need for tungsten hammer or power spring.

I set the power wheel at 7 and the manual hammer screw adjuster at max preload, just below the point at which the trigger sear won’t catch. I set the reg pressure at 142bar. Take 3 shots and record the speeds, decrease the hammer screw manually by 1 turn and measure speed again.m, taking 3 shots each time. Keep doing this and observe the change in speed as hammer is reduced manually, keeping your power wheel set on max (you’ll see why later). It’s possible that as you reduce hammer, speed will increase (as others have mentioned, sometimes too much hammer doesn’t open the valve enough). In any case, keep reducing the manual hammer screw 1 turn until you see the speed declining, which indicates you’re past the sweet spot of hammer tension. Then return the hammer spring tension (manually with the screw) to the point where the speed was highest (for me it was 980-990). Now for the trick that gets slugs shooting well out of a compact: Increase the reg pressure by ~5 bar and check the speed again (without changing hammer tension). The speed should drop to 960 or so. Increase reg pressure again in tiny increments until you get settled at 950. What this does is ensure that you’re getting a shorter and sharper burst of air and this is the trick to getting good slugging out of a compact. All the while you should have kept your power wheel at max (7 on my wildcat). This becomes your max speed slug setting and you can change the wheel to lower setting for other ammo. For example at level 1, mine will shoot Hades at 800fps. Makes for a very versatile rig. Good luck!
 
I have a Wildcat Mk3 BT 500mm shooting the 23 grain Javelin 218s at 950fps and it’s very accurate and consistent. I understand that it has the same guts as the Maverick so you should be able to copy what I did:

To get adequate hammer, I used the stock spring with a Huma 14.5g hammer from their maverick/wildcat/dreamline/etc hammer weight tuning kit. Also used slug probe and pin. No need for tungsten hammer or power spring.

I set the power wheel at 7 and the manual hammer screw adjuster at max preload, just below the point at which the trigger sear won’t catch. I set the reg pressure at 142bar. Take 3 shots and record the speeds, decrease the hammer screw manually by 1 turn and measure speed again.m, taking 3 shots each time. Keep doing this and observe the change in speed as hammer is reduced manually, keeping your power wheel set on max (you’ll see why later). It’s possible that as you reduce hammer, speed will increase (as others have mentioned, sometimes too much hammer doesn’t open the valve enough). In any case, keep reducing the manual hammer screw 1 turn until you see the speed declining, which indicates you’re past the sweet spot of hammer tension. Then return the hammer spring tension (manually with the screw) to the point where the speed was highest (for me it was 980-990). Now for the trick that gets slugs shooting well out of a compact: Increase the reg pressure by ~5 bar and check the speed again (without changing hammer tension). The speed should drop to 960 or so. Increase reg pressure again in tiny increments until you get settled at 950. What this does is ensure that you’re getting a shorter and sharper burst of air and this is the trick to getting good slugging out of a compact. All the while you should have kept your power wheel at max (7 on my wildcat). This becomes your max speed slug setting and you can change the wheel to lower setting for other ammo. For example at level 1, mine will shoot Hades at 800fps. Makes for a very versatile rig. Good luck!
Fantastic tuning advice right there!
 
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Two big assets when diagnosing something like this are:

1) an ACCURATE, RELIABLE chrono. Something like competition electronics ProChrono with a light kit. I have big hopes for the upcoming FX true ballistic radar chrono, but the current FX pocket chrono doesn't cut it for more than a casual field check.
2) a digital reg gauge. I'm partial to the Sekhmet, but the generic one button chinese ones sold by Huma, etc. seem to be OK. It's not uncommon for Wika gauges to be off by 5 to 10bar. On top of that, they are difficult to read for precision.

The reg is easiest to check out. Either it is refilling to the same pressure each time or it isn't.

The chrono tells you not only what your speed is, but also and how consistent it is, which will help inform on the type of issue you are having.

Something else you may want to consider doing (at least while troubleshooting this) is sticking with the factory probe adjusted all the way forward. The pin probe is only good for +10-15fps in the best case scenario, and in the worst case, may cause issues by not seating projectiles deep enough and not loading straight. The factory probe is going to seat any projectile except flat base slugs deeper. Hammer weights make the biggest difference in power potential, and based on the above wildcat tune example, is probably the first change you should try to see if it helps.

Lastly, once you get the power issue figured out, plan on buying a lot more slugs than just two to try out.
 
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I couldn't get RMR's accurate until I hit 980fps
I was up in the 950 range on my Sapsan, but I had to brutalize the valve to do it.

I'm going into my o-ring collection and redoing the #2 reg to see if that's where the leak is, I'd turned it in, BUT was careful not to bottom it out but...may have. As I'm not going out hunting tomorrow, I'll have time in the next few days to work on the regs.
 
Sorry to leave this thread hanging... and thanks to all for the advise, I'll be working through it when the gun settles down.

1. fixed reg leaks, added a total of 14 Belleville washers to reg #2 so I could get the screw down far enough not to leak, FX missed a tolerance...bigley.
2. Bought a new Superior Liner and gave it a polish, has a tight spot but it's going to wait.
3. Flipped to slug side on the transfer port
4. Installed Huma probe, it's a mm too long from the stock probe but...I'll suffer for a while., I'd bought a pin probe but....the hole is .2mm too small...HELLO FX, did you miss the reaming operation? (I've taken note of the issue with using pin probes and will take that into account)
5. Installed new hammer and hammer (polished both) weight, the weight is 1gm heavier than the stock one, don't recall what it is but I'm going to be measuring it later.
6. I've got zero idea which spring is in it, I've got so many, I may not have put the stock spring back it.
I actually had to turn #2 reg DOWN for the pellets work fine in the short time I had to test yesterday. Have the hammer spring adjuster adjusted so the spread is pretty descent, not perfect but close enough. Will be out at 100 yards tomorrow to see if I can get One Minute of Squirrel accuracy with pellets, not fighting the slugs yet but I've got enough springs and weights to get there.